Klasifikasi Lycopodiophyta
Klasifikasi Lycopodiophyta
Klasifikasi Lycopodiophyta
Received: 15 September 2013 Returned for revision: 23 October 2013 Accepted: 28 November 2013 Published electronically: 13 February 2014
† Background and Aims Throughout the history of fern classification, familial and generic concepts have been highly
labile. Many classifications and evolutionary schemes have been proposed during the last two centuries, reflecting
Key words: Bibliography, classification, convergence, cryptogams, Cyatheaceae, fern family concepts, fern allies,
ferns, homology, lycopods, monilophytes, Polypodiaceae, pteridophytes, history of botany.
In commemoration of the 250th birthday of Carolus Linnaeus, gametophyte (Fig. 1A), a haploid plant. Typically gametophytes
Pichi-Sermolli (1958) provided an overview of higher classifica- are photosynthetic, but there are mycoheterotrophic gameto-
tion of pteridophyta (understood to mean at that time ferns and phytes in some fern genera and families (Merckx et al.,
‘fern allies’). He stated that classifications until then had 2012). Gametophytes, often called prothalli, produce gametes
reflected four trends; (1) accepting four major lineages usually through mitosis: male gametes, formed in antheridia, swim to
treated as classes: Psilopsida, Lycopsida, Sphenopsida and the archegonia where female gametes are produced. The
Pteropsida, the last including ferns and seed plants (e.g. mobile, free-swimming, flagellate male cells are the reason for
Jeffrey, 1903; Arnold, 1948); (2) treating ferns and ‘fern allies’ the water dependence of ferns; water is required for their move-
as a group but excluding Psilopsida, treating the latter as ment from one gametophyte to another. Gametophytes can be bi-
related to Bryophyta (Lam, 1948) or as an independent lineage sexual or unisexual, and some can also reproduce vegetatively (a
together with the fossil Psilophytopsida (Rothmaler, 1951); (3) few may have lost the sporophyte stage altogether). From the fer-
maintaining Pteridophyta in their classical sense, including all tilized female gamete, a new sporophyte develops. This life-
vascular cryptogams (e.g. Campbell, 1940; Reimers, 1954); history pattern differs from that in mosses, in which sporophytes
and (4) recognizing the independent divisions Psilophyta, are parasitic on the photosynthetic gametophyte, and from seed
Lycophyta, Sphenophyta, Pteridophyta and Spermatophyta plants. In the latter, male and female gametophytes develop
A B
E F
F I G . 1. Characters of ferns. (A) Gametophyte [Ptisana attenuata (Labill.) Murdock, Marattiaceae]. (B) Sporophyte [Ptisana sp. nov. (Kamau & Christenhusz 638,
EA, K), Marattiaceae]. (C) Circinnate vernation (Sphaeropteris excelsa (Endl.) R.M.Tryon, Cyatheaceae). (D) Sporocarps [Salvinia natans (L.) All., Salviniaceae].
(E) Discrete sori with indusia [Polystichum falcatum (L.f.) Diels non Fée, Polypodiaceae]. (F) Acrostichoid sori [Acrostichum durvillei (Fée) C.Presl, Pteridaceae].
Sori. Sporangia can be organized in various ways. Sometimes to which sporangia are fixed; a sorus can be covered with a scale-
they cover the entire lower lamina of the blade, especially like structure called the indusium (Fig. 1E). The shape and organ-
towards its apex, which is called an acrostichoid sorus ization of the indusium has been an important character for
(Fig. 1F). In most taxa, sporangia are organized in discrete sori higher classification of leptosporangiate ferns and is still
(Fig. 1E). The typical leptosporangiate sorus consists of a stalk employed today, although usually in combination with other
574 Christenhusz & Chase — Trends and concepts in fern classification
characters. It was clear, even before the advent of molecular sys- Salviniaceae; it is clearly an adaptation to their aquatic environ-
tematics, that there is a great deal of convergence in sorus char- ments, where the female gametophyte develops inside the
acters, so on their own they have not reliably revealed a great deal megaspore and is thus protected from the surrounding water.
about relationships. These heterosporous ferns were often placed among ‘fern
allies’, together with the unrelated heterosporous lycopods
Indument. Fern leaves can be glabrous or densely covered in hairs (Selaginellaceae, Isoëtaceae), but heterospory has evolved inde-
or scales. The shape and anatomy of these hairs are often used to pendently in these lineages (and again in seed plants, which are
diagnose species, but this is rarely useful at higher levels of clas- also heterosporous) and is not necessarily associated with aquatic
sification. Scales of the rhizomes have been demonstrated to be habitats in those lineages. Spores in heterosporous ferns are
conservative and phylogenetically informative, especially if formed in special structures called sporocarps (Figs 1D, 4I).
clathrate scales are present (these are translucent like a stained- All other ferns and Lycopodiaceae are homosporous, the plesio-
glass window). morphic condition.
With this explanation of terms, we hope to have clarified the
Spores. Spore characters are useful in classification and phylo-
various characters used in fern classification, which should
genetically informative, and they have also allowed calibration
make a historical overview easier to follow.
of DNA-based phylogenetic trees with the ages of fossil
spores. Most remarkable are perhaps the heterosporous ferns.
Heterospory is a condition in which a single sporophyte produces H ISTOR ICAL OVE RV IEW
a smaller number of large spores, megaspores, that develop into
Difficulties with artificial classification and ‘natural’ systems
female gametophytes and, more typically, numerous micro-
spores that develop into male gametophytes. In ferns, this condi- As with all botanical studies, the nomenclatural history of fern
tion is only found in two groups of aquatics: Marsileaceae and taxonomy starts with Linnaeus (1753, 1754), who first attempted
Christenhusz & Chase — Trends and concepts in fern classification 575
to organize ferns based on the shape and position of sori on authors for 30 years, probably as a result of no further insights
leaves; this use of a single character produced an artificial but into other characters that could be used in addition to or in place
easily used classification. Fern diversity and anatomy had been of sori and indusia. They were also, for instance, the basis of a clas-
addressed in earlier studies (e.g. Cesalpino, 1583; Grew, 1682; sification by Desvaux (1827), who, due to a more detailed study of
Malpighi, 1675; Morison, 1699; Van Rheede tot Drakestein, soral characters, increased the number of genera to 79 in five fam-
1678 – 1703; Plumier, 1705; Petiver, 1712), but it is important ilies (Marsilées, Lycopodiées, Osmondées, Marattiées, Filicées),
to note that at the time little was known about the life cycle of improving somewhat on the intrinsic naturalness of Swartz’s clas-
ferns. Linnaeus’s sexual system, based on the number of sification. This informal use of families by Desvaux contrasted
stamens and pistils (the so-called ‘sex organs’ in flowering with all other fern taxonomists, who did not apply the family
plants), functioned well for artificially classifying angiosperms, concept to ferns and preferred to use other categories. An impres-
but it was impossible to place ferns in a system based on numbers sive 1666 species were presented by Desvaux (1827), of which
of male and female parts. Ferns were therefore placed in many species were new, but they were mechanically placed in
Cryptogamae, among mosses, algae, fungi and even some animals genera solely following the classification of Swartz (1801). This
(corals, sponges, etc). In his Cryptogamia filices Linnaeus (1753, system was soon challenged because species too different in
Sp. Pl. 2: 1085–1100) recognized 16 genera and 174 species: other characters, and obviously not closely related, were often
re-application of the Swartzian system, which lasted for another At the turn of the century, phyletic classifications of ferns were
50 years as the most often used fern classification. also being compiled elsewhere, the first being a treatment by the
Although sporangium and sorus characters remained predom- British botanist Bower (1889), who based his ideas on his elab-
inant as the basic framework for fern classification thanks to orate studies on anatomy, development and morphology. In his
Hooker’s prominence, some interest in applying other characters three-volume work, The ferns, Bower (1923 – 1928) recognized
to classification continued; Fée, who published the elaborate 12 families, and in Polypodiaceae, the first major use of this
series Mémoires sur la famille des fougères (Fée, 1844 – 1873), now ubiquitously applied name, he recognized six evolutionary
which included Genera filicum (6th and 7th Mémoire), empha- lineages. This phyletic classification was, however, problematic,
sized an even wider range of characters for generic delimitation mainly due to an emphasis on the location of sori on the leaf
than Presl and recognized approx. 188 genera. The first Mémoire blade.
dealt entirely with characters of ferns useful for classification and Copeland (1929), who attempted to arrange the East Asian
focused on venation. It also reviewed other characters, seeking genera into a phyletic sequence, was the first to address this
new ones in fertile structures. He applied, for instance, characters problem and suggested that a larger Polypodiaceae would be
of the spores and number of cells in the annulus. The last charac- more natural. The tree-fern lineages were included, not making
ter was not taken up by subsequent pteridologists, but it was re- Polypodiaceae natural in the Bowerian sense, but this wider
when other characters such as habit are more obvious to distin- He first defined his concept of Pteridophyta as ‘chlorophyllous,
guish groups. Copeland also provided a good overview of the autotrophic land plants with antithetic (heterophasic) change of
concepts of fern classification preceding his magnum opus. He generations, and both generations organically independent’. In
presented a similar number of taxa to Ching (1940), which this way he included the lycopods with ferns in a single lineage.
Christensen stated had much to do with the two having the Reimers provided a developmental scheme in which fern lineages
same generic concept. However, Ching still recognized 28 were set out on a time scale, all essentially originating from
genera more than Copeland, so Christensen’s criticism was not Psilophytales (in which he included the fossils Rhynia R.Kidston
entirely justified. & W.H.Lang and Psilophyton J.W.Dawson) in the early
Holttum (1947) revised the classification of Christensen Devonian (320 million years ago). Modern Psilotales are directly
(1938), which resulted from a detailed study of Malayan ferns. derived from them in his scheme, which was the general idea at
It had been customary to place all leptosporangiate ferns in a the time and one that prevailed until this century. We will not go
broad Polypodiaceae, apart from a few easily recognizable fam- into the classification of his fossil taxa here, although we admit
ilies such as Osmundaceae (considered intermediate between that to come to a good classification of ferns, fossil lineages will
leptosporangiate and eusporangiate ferns), Cyatheaceae (the have to be included. It is, however, not within the remit of this
tree ferns with a helicogyrate annulus), Gleicheniaceae (with a paper to compare fossil classifications with those for extant ferns.
of extant taxa, and it has therefore been unfortunate that this clas- 1970s, chromosomes of around 15 % of fern species had been
sification did not find wider acceptance. counted, and Walker (1973) provided a good review of how cyto-
Alston (1956), while preparing an account for the Flora of West logical information could help in unravelling previous problems.
Tropical Africa, came to disagree with the classification of Holttum Manton (1958) demonstrating, for instance, that Pteridaceae of
(1947). He segregated Lindsaeaceae from Dennstaedtiaceae and Copeland (1947) did not form a uniform lineage, with Pteris,
maintained Vittariaceae as separate from Adiantaceae [although this Cheilanthes Sw. and Adiantum having chromosome numbers
had already been done by Reimers (1954) at the subfamilial level]. based on 29 or 30, and the other group (corresponding to
He also segregated Aspleniaceae, Aspidiaceae, Athyriaceae the ‘dennstaedtioid group’) showing a wide range of basic
and Blechnaceae from Holttum’s Dennstaedtiaceae, and he numbers, even within a single genus. Chromosome numbers
described Athyriaceae and Lomariopsidaceae. The movement of continued to play a role in classification for several decades,
genera by various authors between Athyriaceae, Aspidiaceae only to be replaced by molecular phylogenetics in the 1990s, pro-
and Dennstaedtiaceae shows, however, that relationships among viding important insights into relationships of species, genera
these genera were far from understood. and sometimes families. Mehra (1961) finalized the application
Pichi-Sermolli (1958) subdivided Pteridophyta into six classes, of chromosome numbers and described phyletic lineages in
which were mixtures of living and fossil taxa with the two ex- terms of their cytological evolution, but this information was
resulted in movement of genera into different families and taxonomy of all groups despite large amounts of genetic
changes between family and subfamily names. He did attempt (DNA) data having been collected. Knowing the phylogenetic
to place his families and subfamilies into an evolutionary tree does not, of course, tell us how to delineate families or
scheme, although also here there are some odd placements. genera.
Plagiogyriaceae, for instance, are in his scheme derived from Mickel (1974) criticized the development of phyletic classifi-
Osmundaceae, which is a strange placement for a group that cations over the preceding years, stating that circumscription was
has sporangia bearing remarkable similarities to those of often ‘ill-founded and the relationships were often based on
Cyathea (Hooker and Bauer, 1842). Blechnaceae, to which speculation rather than solid evidence’. Mickel stressed the
Plagiogyria (Kunze) Mett. generally was thought to be related need for proper evaluation of homologous characters, and he dis-
due to superficial similarity, are the only unplaced lineage in cussed some of the major issues of homology, for instance the
Nayar’s scheme in which there had been no attempt to justify pos- different types of scales and development of stelar structures.
tulated relationships. He also pointed out the usefulness of stomata morphology to
Because Pichi-Sermolli (1970b) published a detailed cata- infer phyletic relationships. He then presented a freely drawn
logue of fern family names, Holttum (1971) felt obliged to phylogram, which is backed by a discussion of characters, but,
comment on it and pointed out that ‘in the case of family even though the evidence was sound, the choice of characters
which demonstrated that plastid DNA is maternally inherited in and Davalliaceae are the closest relative of the Polypodiaceae
this cheilanthoid fern. clade. Tectaria was found to be closer to Oleandraceae rather
In an early phylogenetic study, Hasebe et al. (1993) sequenced than to Dryopteridaceae, with which it was usually associated.
four ferns to infer the relationships of ferns to other land plants. Again, Dennstaedtiaceae were found to be polyphyletic,
Sequencing was still a laborious process, but, due to the develop- but this time with three lineages emerging; Lonchitis and
ment and improvement of in vitro DNA amplification [ polymer- Orthiopteris Copel. fell in a clade separate from Lindsaea
ase chain reaction (PCR)], a much larger number of taxa could be Dryand. Vittariaceae were found deeply embedded in
studied, and rbcL data for ferns quickly accumulated. Hasebe Pteridaceae and strongly supported as sister to Adiantum.
et al. (1994) developed effective primers to sequence rbcL in Tree ferns (including Metaxyaceae, Loxsomataceae and
ferns; their paper focused on leptosporangiate lineages, and it Plagiogyriaceae) were monophyletic and diverged early from the
showed monophyly of heterosporous ferns within the leptospor- rest of the leptosporangiate taxa, just after the divergence of hetero-
angiate clade. They identified all main lineages in ferns and sporous ferns. No clear placement was found for Psilotaceae, but
showed that Dennstaedtiaceae were not monophyletic when lind- in one of their analyses (neighbor joining), Psilotum Sw. and
saeoids were included; they also found Vittariaceae resolved Tmesipteris Bernh. were sister to Ophioglossaceae, a portent of
close to Adiantum. Possible changes in classification were sug- what would be later found.
Polypodium
Grammitis
Campyloneurum
Microsorum
Lepisorus
Pyrrosia Polypodioideae
Platycerium
Selliguea
Drynaria
Loxogramme
Davallia Davallioideae
Oleandra Oleandroideae
Triplophyllum
Tectaria Tectarioideae
Arthropteris
Nephrolepis Polypodiaceae
Dracoglossum Lomariopsidoideae
Lomariopsis
Cyclopeltis
Ctenitis
Polystichum
Dryopteris
Arachniodes Dryopteridoideae
Polybotrya
F I G . 3. Summary phylogenetic tree showing relationships of a representative selection of fern genera based on molecular (DNA) data, modified from Schuettpelz and
Pryer (2007), Lehtonen (2011), Rothfels et al. (2012) and Schneider et al. (2013).
582 Christenhusz & Chase — Trends and concepts in fern classification
rbcL data for the same 50 taxa. They also found Ceratopteris and taxa. It seems that a new colloquial name has been coined for
Vittaria Sm. among pteridoid ferns and Plagiogyria in the tree- no particular reason other than providing a scientific-sounding
fern lineage. Dennstaedtiaceae formed two unresolved lineages, synonym for the word ‘fern’; in fact, it is often used in paren-
but with Lindsaea not grouping with either of these. theses after the word fern, so ‘monilophyte’ is superfluous. It is
Heterosporous ferns and Schizaeaceae formed two independent an alternative to the word ‘pteridophyte’, which traditionally
lineages also at unresolved positions within leptosporangiate included all ferns plus lycopods; thus, an alternative, similar
ferns. sounding word was coined, without taking notice of its etymol-
Plastid 16S ribosomal DNA sequences were then applied to ogy: ‘bead-plant’ being as uninformative as ‘wolf-plant’ or
address the placement of ‘fern allies’. Manhart (1995) found ‘lycophyte’, which should correctly be called clubmoss (in the
Psilotum as sister to Tmesipteris, together forming a well- English vernacular) or lycopod (based on Lycopodium and refer-
supported sister group to Ophioglossaceae. This relationship ring to the vernacular ‘wolf-claw’ of many languages).
seemed odd at first, but it is now supported by morphological Psilotaceae were not included in the study of Kenrick and
characters (Schneider, 2013). When the problematic lycopod Crane (1997), but Pryer et al. (2004) included these to show
Selaginella P.Beauv. was removed from their matrix (which they also belong to the fern clade. Critical taxa were included
perhaps had been causing some sort of spurious attraction of in this data set and additional plastid (rbcL, atpB and rps4) and
(Corvez et al., 2011). Morphological data have since been com- consensus classification, aiming to define monophyletic families
bined with molecular data in analyses with some important and genera with synapomorphies.
insights (e.g. Schneider, 2007; Lehnert et al., 2009; Lehtonen Some of the notable discrepancies are due to the traditionally
et al., 2010; Sundue, 2010; Sundue et al., 2010). broader generic concepts used by workers in the Neotropics com-
In a new edition of A. Engler’s Syllabus of Plant Families, pared with those in tropical Asia. Now we can combine the data
Fischer (2009) adopted findings of recent molecular analyses on these taxa and come to a consensus classification resulting in
and treated Lycophytina as separate from Euphyllophytina. evolutionarily defined natural genera and families. With the
Within the latter, he accepted super-class ‘Moniliformopses’ of wealth of data currently available (e.g. Eiserhardt et al., 2011;
Kenrick and Crane (1997), comprising all ferns, Equisetaceae Lehtonen, 2011; Lehtonen et al., 2012; Rothfels et al., 2012;
and Psilotaceae. A synopsis was provided on classification of Zhang and Zhang, 2012; Liu et al., 2013; Schneider, 2013;
this group, and it included all fossil taxa, which in many cases Schneider et al., 2013) it is now possible to compare generic con-
were placed in families consisting of exclusively fossil taxa. cepts across continents, applying a global concept of family and
We did not check all fossil families, but we noticed that nomen- genus.
clatural priority of family names was not always taken into
account. For the extant taxa, it simply followed the classification
A B C
D E F
J K L M N
F I G . 4. Sori of major fern lineages. (A) Equisetales, Equisetum telmateia Ehrh. (B) Ophioglossales, Botrychium virginianum (L.) Sw. (C) Psilotales, Psilotum nudum
(L.) P.Beauv. (D) Marattiales, Marattia cicutifolia Kaulf. (E) Osmundales, Todea barbara T.Moore. (F) Hymenophyllales, Trichomanes cupressoides Desv. (G)
Gleicheniales, Dicranopteris linearis (Burm.f.) Underw. (H) Schizaeales, Lygodium volubile Sw. (I) Salviniales, Marsilea drummondii A.Braun. (J) Cyatheales,
Alsophila dealbata (G.Forst.) C.Presl. (K) Polypodiales, Dennstaedtia punctilobula (Michx.) T.Moore. (L) Pteris usambarensis Hieron. (M) Eupolypods,
Asplenium caudatum G.Forst. (N) Dryopteris sieboldii (T.Moore) Kunze.
the term ‘fern’, which as noted above has in the past often as independent lineages (‘sphenophytes’, ‘psilotophytes’, ‘mar-
included Equisetaceae and Psilotaceae, although alternatively attiophytes’), although this does not reflect their membership in a
the early branching lineages of the fern clade could be treated clade with the rest of the ferns.
Christenhusz & Chase — Trends and concepts in fern classification 585
To illustrate the changing ideas of how ferns should be classi- together and which has been used as the synapomorphy for the
fied, we focus below on a number of groups and genera and de- order Cyatheales. This leads to a discussion of what defines an
scribe the variation in opinions that have existed about how order relative to a family. One character used is the age of diver-
best to handle their taxonomy. gence between the individual lineages, which in the case of
Leptosporangiate ferns are a natural group, forming the crown Cyatheales is Late Jurassic (Schneider et al., 2004), similar to
group of ferns including the vast majority of species. In the past, the age of many angiosperm families. Cyatheales are too highly
most of these have at one time been included in a single family, divided at the family level, and the lineages should still be
Polypodiaceae (or variants such as Filices or Dennstaedtiaceae, revised taxonomically on the basis of synapomorphies and mono-
variously including Osmundaceae, tree ferns and gleichenioid phyly. In the classification below, the established families are
ferns), resulting in great variability in application and circum- treated at the subfamilial level, allowing movement of genera
scription of this family. The concept changed from including between them without altering their family placement. Not all
the majority of the leptosporangiate ferns to the most recent genera in Cyatheaceae sensu lato are tree like; they include trunk-
concept of those having scaly creeping rhizomes with abaxial less Plagiogyria, Metaxya and Loxsoma R.Br. They also include
(rarely marginal), rounded to elliptic, elongate or acrostichoid, Hymenophyllopsis (Lellinger, 1984), a group of small ferns
exindusiate sori. The grammitid ferns were traditionally not from the Guayana Highlands in South America. This genus was
embedded in Blechnum (specifically related to B. serrulatum which are microscopic, and in the vascular structure of petioles
Rich.), which should also include Brainea J.Sm., Doodia (generally an arch of vascular strands in a U-shape, except in
R.Br., Pteridoblechnum Hennipm. and Sadleria Kaulf. Hypodematiaceae). The second lineage (eupolypods II) includes
Lomaria was based on the Australian L. nuda (Labill.) Willd., Aspleniaceae sensu stricto, Athyriaceae, Blechnaceae, Cysto-
and Blechnum is based on the Neotropical B. occidentale L.; pteridaceae, Diplaziopsidaceae, Hemidictyaceae, Onocleaceae,
the European species that has characters of the two was placed Rhachidosoraceae, Thelypteridaceae and Woodsiaceae (sensu
in Spicanta C.Presl, an intermediate genus created to solve the Christenhusz et al., 2011), which share the character of a laterally
problem of intergrading morphology. The current consensus is attached indusium (except in some Thelypteridaceae) and two
to apply a broad concept of Blechnum, but further studies on vascular bundles in their petioles. Even though synapomorphies
the evolution of Blechnaceae are needed to assess which, if are few and not visible to the naked eye, it is possible to treat these
any, of the segregate genera should be maintained. as two broad families instead of the current 18 (or 20) based on
Acrostichum was a genus applied initially to all ferns with sori their shared characters. Within these two lineages, a plethora
that were acrostichoid (Fig. 1F), i.e. distributed as a solid mass of families has recently been proposed (including the recent
across the back of the frond rather than organized in separate, dis- segregation of Arthropteridaceae from Tectariaceae; Liu et al.,
crete structures. We know today that an acrostichoid fertile 2013), and many genera have changed family (e.g.
to distinguish these families, and their history has been as compli- [LYCOPODS; 3 families, 5 genera, approx. 1300 species]
cated and controversial as those for most fern families. LYCOPODIIDAE BEK.
A second common trend has been the use of minute characters
to circumscribe narrowly circumscribed genera, and some Lycopodiales DC.
authors have used phylogenetic trees as the basis for placing Lycopodiaceae P.Beauv. 1 (3/approx. 400)
every pair of sister species into separate genera. Following (Huperzia Bernh., Lycopodiella Holub,
such episodes, another trend typically emerges, which expands Lycopodium L.)
generic limits and subsumes such small genera into larger Selaginellales Prantl
ones, often redefining the original generic concept to fit this Selaginellaceae Willk. (1/approx. 750)
greater number of species with more divergent morphology. (Selaginella P.Beauv.)
Even though this waxing and waning of generic limits may even- Isoëtales Prantl
tually produce a consensus taxonomy, it destabilizes nomencla- Isoëtaceae Reichenb. (1/approx. 140)
ture and confuses the users. Ultimately, such instability hinders (Isoëtes L.)
research on ferns by non-taxonomic researchers, thereby retard-
[FERNS; 21 families, approx. 212 genera, approx. 10 535
ing progress on understanding their biology, conservation,
7
Subfamily Loxsomatoideae (C.Presl) Christenh., stat. nov. is based on full
and direct reference to the Latin description and type of Loxsomataceae in Presl
(1847: 31). The two genera in Loxsomatoideae are similar, and their separation is
mainly based on geographical isolation. They may be better treated as a single
genus.
8
Subfamily Culcitoideae (Pic.Serm.) Christenh., stat. nov. is based on full
and direct reference to the Latin description and type of Culcitaceae in
4
Phylogenetic analysis of Osmundaceae clearly placed the cinnamon fern as Pichi-Sermolli (1970a: 207).
9
sister to all other Osmundaceae, which should thus be treated as Osmundastrum Subfamily Plagiogyrioideae (Doweld) Christenh., stat. nov. is based on full
cinnamomeum (L.) C.Presl (Yatabe et al., 1999). Todea and Leptopteris form a and direct reference to the Latin description and type of Plagiogyriidae in Doweld
clade and could be merged as a single genus, although to maintain stability we (2001: XII).
10
have tentatively accepted Leptopteris here. Even though Cyatheoideae are in need of further study, there appears to be a
5
The filmy ferns are composed of two subclades, corresponding to the current consensus of four genera (Korall, 2006, 2007; Christenhusz et al., 2011),
traditional genera Hymenophyllum and Trichomanes, which we accept here. The although Gymnosphaera is not yet well defined and, because many combinations
subdivision of Trichomanes into eight genera as done by Ebihara et al. (2006) is are not yet made, it can be argued that the subfamily is best treated as including a
possible, and the genera are stable and backed up by morphological characters. single large genus. Hymenophyllopsis, previously placed in its own family, and
However, we think that non-specialist users may find these genera difficult to Cnemidaria C.Presl are embedded in Cyathea and should be treated as part of that
apply, and these are thus probably better treated at the subgeneric level within genus in any classification of the subfamily.
11
Trichomanes. We still cannot make an informed decision about whether or not to maintain
6
Subfamily Lygodioideae Christenh., subfam. nov. is based on full and direct Orthiopteris as separate from Saccoloma. Phylogenetic study and monographic
reference to the Latin diagnosis of Lygodium by Swartz (1801: 106). The genus revision of Saccolomataceae are needed, although the two genera are
Lygodium is the type of this subfamily. undoubtedly closely related.
Christenhusz & Chase — Trends and concepts in fern classification 589
Polypodiaceae J.Presl & C.Presl ¼ eupolypods I20 (Cyclopeltis J.Sm., Dracoglossum Christenh.,
(approx. 76/approx. 4070) Lomariopsis Fée, Nephrolepis Schott)
subfamily Didymochlaenoideae Christenh.21 subfamily Tectarioideae B.K.Nayar25
(Didymochlaena Desv.) [Aenigmopteris Holttum, Arthropteris J.Sm.,
subfamily Hypodematioideae Christenh.22 Hypoderris R.Br.,
(Hypodematium Kunze, Leucostegia C.Presl) Pteridrys C.Chr. & Ching, Tectaria Cav. (approx. 250),
subfamily Dryopteridoideae Link23 Triplophyllum Holttum]
[Adenoderris J.Sm., Arachniodes Blume (approx. subfamily Oleandroideae Crabbe, Jermy & Mickel
110), Arthrobotrya J.Sm., Bolbitis Schott, Coveniella (Oleandra Cav.)
Tindale, Ctenitis (C.Chr.) C.Chr, Cyclodium C.Presl, subfamily Davallioideae Hook.26
Cyrtomidictyum Ching, Dryopolystichum Copel., [Davallia Sm., Davallodes (Copel.) Copel.]
Dryopsis Holttum & P.J. Edwards, Dryopteris subfamily Polypodioideae B.K.Nayar
Adanson (approx. 375), Elaphoglossum Schott tribe Loxogrammeae R.M.Tryon & A.F.Tryon
(approx. 750), Lastreopsis Ching, Lomagramma [Dictymia J.Sm., Loxogramme (Blume) C.Presl]
J.Sm., Maxonia C.Chr., Megalastrum Holttum, tribe Drynarieae Chandra27
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